Polarization agility in an RF radiator module for use in a phased array

TLDR: In this paper, a 90° coupling circuit cascaded with a pair of hybrid mode latchable phase shifters provides polarization agility for an RF radiator module of the type typically used in a phased array.

Abstract: A 90° coupling circuit cascaded with a pair of hybrid mode latchable phase shifters provides polarization agility for an RF radiator module of the type typically used in a phased array. For example, such radiator modules typically may utilize an active microwave integrated circuit (MIC), a monolithic microwave integrated circuit (MMIC) or a passive reciprocal hybrid mode element (RHYME) circuit. These circuits are arranged to provide duplex RF transmit/receive functions with controllable phase shifts at each radiator site in a phased array. By appropriately setting the two controllable phase shifters to different combinations of phase shifts (e.g., 0° and/or 90°) to a dual orthogonal mode radiator, different spatial polarizations for RF radiator transmit/receive functions can be defined. The radiator itself may include a square or circular waveguide including, in some cases, a reciprocal dielectric quarter-wave plate and a non-reciprocal ferrite quarter-wave plate. If a square waveguide is utilized, then 0°, 90° hybrid mode latchable phase shifters may be arranged on either side of a common ground plane with direct waveguide coupling into a septum polarizer waveguide section of the radiator element. A 90° Lange hybrid coupler also may be used by itself in conjunction with an electrically rotatable ferrite quarter-wave plate radiating element to achieve a certain degree of polarization agility.